Process for reclaiming film scrap with an alcoholic solution of sodium peroxide



. I No Drawing.

Patented ch. 9, v

CHARLES .E. ALLEN, OF

nocHEs'rER, NEW YORK, Ass-remort- TO EASTMAN xom x corr- IPANY; OF ROQHESTER,,NEW YORK, ACOR-PORATION' OF NEW YORK PROCESS FOR RECLAIMING FILM sonar! WITH AN ALCOHOLIC soru'rron' orsonn m PEROXIDE Application filed May 24,

This invention relates to the reclamation of dyed photographic film scrap having a base of a cellulosic derivative and more particularly to a process for reclaiming dyed photographic film scrap which has a base of cellulose nitrate.

For many photographic purposes, photographic films are tinted -or colored with suit-- able dye which acts upon the film base or support to color it. The dye 'is usually applied to the film support upon the side opposite to which the light-sensitive silver hallde emulsion is applied; the dye so appli does not normally penetrate more than a fraction of a thousandth of an inch. Various methods have been employed for removing this dye from the film base in order that the film base may be re-employed for various purposes, such as the manufacture of new film, lacquers, fabric coatings, etc.

Under normal practice, the silver halide emulsion is removed'from the film by the'u'se of hot water following which the dye is i bleached and/or leached out of the film base.

Q Leaching with alcohol has been employed with success in some phases of film reclamation and bleaching of the film scrap is sometimes employed subsequentato the emulsion removal but prior to the leaching step.

It is ainong'the objectsof my invention, to provide a simplifiedsand efficient process 7 which eliminates many of the steps and muchof the cost and uncertainty of some of the prior known processes. It is a further object to provide a processfor reclaiming cellulosic derivative scrap. Other objects will beapparent herein.

I have found that dyed cellulose nitrate film base may be reclaimed in a very simplified manner,-'after'the silver halide emulsion has been removedby hot water treatment from the cellulosenitrate base by subjecting the, film scrap to the action of alcohol into which has been carefully stirred a small quantity of sodiumperoxide. Such treatment is neither a leaching nor a bleaching process but is a single step method by which the surface of the cellulose nitrate film base is hydrolyzed and actually removed from the. film. By so timing the treatment, the minimum amount- 1930. Serial a... 455,447.

of surface thickness may be hydrolyzed so as just to remove that port-ion of the surface into which the film dye has penetrated or the amount of sodium peroxide stirred into the alcohol may be. so limited that it is just slightly in excess of that necessary to hydrolyze the film base to the-same depth as that to which the dye has penetrated.

of sodium peroxide may be slowly added with thorough stirring to one gallon of ethyl alcohol. The clear liquid is then decanted off As an example of my process, 2 to 30 grams v .60

and poured over approximately one pound of cellulose nitratefilm scrap base from which the silver halide emulsion has previously beenremoved by hot water treatment. .This treatmentis carried on at approximately 90 to 120 F. and the duration of the treatment may be from 2 minutes to l hour depending somewhat upon the colors being treated and "the depth to which the color has penetrated into the film base. The film is, of course, well agitated while being treated. Thetreatment I virtue of any oxidizing action of the peroxide but by virtue of the fact that the sodium peroxi de reacts with the waterwhich is pres-- ent in the alcohol employed to form caustic soda which goes into solution in the alcohol. The resulting alcoholsolution. of caustic hy @drolyzes the surface ofzthe film scrap base I added to it. This hydrolysis is permitted to continue until it has penetrated to the same distance as the dye has penetrated. The hydrolyzed layer is soluble in the alcohol or alcohol and water mixture used with the sodium peroxide, and is consequently removed. Subsequent-washings remove the remaining 211- kali and products of reaction so that clear 1m scrap results Merel because of the above specific example, do not intend to be limited in the spirit or scope of my invention, inasmuch as it will be apparent that various alcohols may be employed, so long as the alcohol is not a solvent of the film base and will dissolve the caustic added thereto. Obviously other compounds may be added to the alcohol such, for instance, as potassium peroxide, etc., to roduce a similar result, as well known to t ose skilled in the art. All of these modifications and equivalents are, of course, to be considered within the scope of the claims appended hereto.

What I claim as my invention and desire to be secured by Letters Patent of the United States is:

1. The process of removing dye from cellulose nitrate film scrap base which comprises treating the scrap with alcohol to which sodium peroxide has been added;

2. The process of removing dye from cellulose nitrate film scrap base which comprises removing the silver halide emulsion from the film base and then hydrolyzing the surface of the base with an alcohol solution to which sodium peroxide has been added.

Signed at Rochester, New York, this 20th day of May, 1930.

CHARLES E. EN. 

